It is known to use fluid driven projectiles or scrapers for the removal of mud, slime, metal oxides or other deposits from the interior wall of a condenser or similar tube. Such scrapers generally comprise one or more fixed blades, bristles, or wire pieces which extend outwardly from a projectile shaft. When the projectile shaft is inserted into a tube, the scraper elements contact the tube wall to clean the wall upon fluid propulsion of the scraper through the tube. Usually, the projectile shaft will have a flexible rear terminal section that is cylindrical in shape, with a diameter slightly greater than the inner diameter of the tube, with fluid pressure exerted on the rear terminal section to drive the scraper through the tube. The tube can thus be cleaned without the need for any attached and externally manipulated line or handles. Examples of such tube cleaning projectiles are described, for example, in U.S. Pat. No. 1,598,771; 2,170,997; 2,734,208 and 4,281,432.
While such tube cleaning projectiles are efficient in cleaning of deposits from the interior walls of tubes, certain deposits referred to as scale, containing calcium or silicon, are formed as hard coatings on the interior wall which are resistant to complete removal by such projectiles. Such hard deposits, if not removeable by the scrapers, because of difficulty in breaking up the hard deposit, are usually removed by an acid wash or are left on the wall, which results in inefficient heat transfer between the tube contents and the outer tube environment. A need thus exists for a device that will break up such hard deposits so that those deposits can be removed from the interior wall of the tube by existing scrapers.
It is an object of the present invention to provide a tube cleaning tool for loosening of hard deposits collected on an interior wall of a tube.
It is another object of the present invention to provide a method for the removal of hard deposits from the interior wall of a tube, such as a condenser tube.